Field of the Invention
The present invention relates to a video signal recording and reproducing apparatus which is capable of recording video signals and reproducing them simultaneously with the recording, more particularly relates to a video signal recording and reproducing apparatus having a better reliability.
The advances made in image processing technology and recording technology have made it become possible to record video signals on a recording medium such as hard disc. By recording video signals on such a randomly accessible recording medium, the processing of editing etc. can be easily carried out. As such an apparatus for recording video signals on a randomly accessible recording medium and effectively utilizing them, there also exists an apparatus capable of performing reproduction at almost the same time as that for recording.
An example of an apparatus capable of performing simultaneous recording and reproduction will be explained by referring to FIGS. 1A and 1B.
FIG. 1A is a view of an example of the configuration of an apparatus capable of performing simultaneous recording and reproduction; while FIG. 1B is a view of the operation of that apparatus.
As shown in FIG. 1A, a video signal recording and reproducing apparatus 900 is constituted by a simultaneous recording and reproduction device 910 for recording and reproducing video signals and a control use computer 920 for controlling the simultaneous recording and reproduction device 910.
The simultaneous recording and reproduction device 910 is a recording device using a hard disc as the recording medium. The hard disc device is provided with a recording head and a reproduction head operating independently from each other. By this, the recording and reproduction can be carried out in parallel. Accordingly, as shown in FIG. 1B, even a just recorded video signal can be immediately reproduced and output delayed by exactly a time .DELTA.T, that is, the time of rotation of the disc from the position of the recording head to the position of the reproduction head.
Of course, since the recording medium is a hard disc, so the video signals can be reproduced at random.
However, a hard disc device has a problem in that the reliability is very low in comparison with a VTR apparatus which has been the main recording medium for recording video signals heretofore.
In a hard disc device, crashes etc. are caused even by a slight shock. The probability of occurrence of damage is very high in comparison with a tape recorder device. If such damage once occurs, there arises a problem in that it becomes impossible to record video signals and reproduce recorded signals. Particularly, in broadcasting stations, where effective use is made of such apparatuses capable of performing simultaneous recording and reproduction, there are many cases where such apparatuses are transported to the news site for use, so the probability of occurrence of damage is even higher.
As a countermeasure in order to deal with such damage, it has been considered to process recorded video signals separately by a VTR apparatus. However, if two apparatuses have to be operated for one video signal, the operatability is poor. In addition, this complicates and enlarges the size of the system. This is therefore not a suitable countermeasure.
Further, in the above simultaneous recording and reproducing apparatus, in the case of performing a nonlinear editing of video signals recorded in other apparatuses, the video signals must be transferred to that apparatus, so there also exists a problem in that the operation was troublesome and a long time was taken. Namely, there have been demands for easier utilization of the recorded video signals.